Seedless Watermelon Having Small Fruit

ABSTRACT

The present invention is a novel method which results in the production of small seedless watermelon fruit having an average fruit weight of less than 12.0 pounds. The novel method involves using small tetraploid parental lines to produce small triploid hybrid seed.

CROSS REFERENCE

This application is a continuation of U.S. application Ser. No.13/359,140 filed Jan. 26, 2012, which is a continuation of U.S.application Ser. No. 12/567,326 filed Sep. 25, 2009, which is acontinuation of U.S. application Ser. No. 11/446,123 filed Jun. 5, 2006(abandoned), which is a continuation of U.S. application Ser. No.10/323,603 filed Dec. 18, 2002 (patented), which claims priority under35 U.S.C. §119(e) to Provisional Patent Application Ser. No. 60/340,276,filed Dec. 18, 2001, all of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a novel seedless watermelon having anaverage fruit weight of less than 12.0 pounds. The present inventionalso relates to a seedless watermelon seed, a seedless watermelon plant,seedless watermelon variety, and a seedless watermelon hybrid and tomethods of producing seedless watermelon fruit.

Watermelon belongs to the family Cucurbitaceae. Watermelon iscommercially grown from either seed or transplants. Citrullus is amember of the family Cucurbitaceae. The Cucurbitaceae is a family ofabout 90 genera and 700 to 760 species, mostly of the tropics. Thefamily includes pumpkins, squashes, gourds, melons, cucumber,watermelon, loofah, and several weeds. A bitter-fruited form ofCitrullus vulgaris appears to be the ancestor of the cultivatedwatermelon.

Successful watermelon production depends on attention to variouscultural practices. This involves soil management practices with specialattention to proper fertilization, crop establishment with appropriatespacing, weed control, the introduction of bees for pollination, andsuitable pollenizers for seedless watermelon, irrigation and pestmanagement. Watermelon fruit size and shape; rind color; thickness andtoughness; seed size, color and number; and flesh color, texture,soluble solids and freedom from fruit defects are all importantcharacteristics to be considered in selection of watermelon varieties.In addition, seedless watermelons should be free of hard seeds and haveundeveloped seeds that are small and innocuous.

Watermelon crops can be established in the field from seed or fromtransplants. Transplanting is becoming more common because transplantingusually results in earlier crops than those that are direct seeded.Transplants are used extensively to establish seedless watermelonplantings. Diploid and triploid watermelon crops can be establishedeasily with high quality transplants. Transplanting helps achieve rapid,complete plant stands, especially where seed costs make direct-seedingrisky and expensive, as is the case with seedless watermelons. Mostwatermelon growers purchase plants from plant growing experts who mayarrange for transport to the field location.

For triploid seedless watermelon production, fruit set and enlargementis dependent upon growth regulators from the pollen grains and fromembryos in developing seeds within the fruit. Inadequate pollinationresults in triploid watermelon fruit that are triangular in shape and ofpoor quality. Inadequate pollination may increase the incidence ofhollowheart. Triploid watermelon flowers do not produce sufficientviable pollen to induce fruit set and development. Therefore, pollenfrom a normal diploid seeded watermelon variety must be provided.Planting the diploid pollenizer variety in the outside row of the fieldand then every third row is recommended. As an alternative, thepollenizer variety has been planted every third plant in each row butthis makes harvesting of the triploid fruit difficult because mixeddiploid and triploid fruit must be separated. This also makes plantingdifficult because blanks must be left where the diploid should go.Maintaining the rotation of three triploid to one diploid is not easilyaccomplished.

Currently, it is important to use a diploid pollenizer variety that ismarketable because between one-quarter to one-half of all watermelonsproduced in the field will be of this variety. The rind pattern and/orshape of the seeded pollenizer fruit should be distinguished easily fromthat of the triploid fruit to reduce confusion at harvest.

It is important that pollen from the diploid pollenizer variety isavailable when female blossoms on the triploid plants are open and readyfor pollination. If planted too early, the diploid variety can set fruitand stop producing male blossoms while the triploid variety is stillproducing many female blossoms. If planted too late, the triploid willbe ready to set fruit but not enough pollen will be ready to providefruit set.

Watermelon plants develop several vigorous and far-reaching vines, thusrequiring large amounts of space for optimum growth and fruitdevelopment. Watermelons have been seeded with about two to about fourfeet between plants in rows about six to about 15 feet apart. This widespacing requires larger field sizes. Also, the wide spacing providedless interplant competition for water. Cultural practices such asirrigation and polyethylene mulch have led to the use of higher plantpopulations. Row spacing of 6-8 feet apart and plant spacing of 2-4 feetare common. Often, with close plant spacing, the individual plant setsfewer fruits, which still reach normal size.

Watermelon plants usually have separate male and female flowers butsometimes produce perfect flowers. To achieve fruit set, pollen from themale flower must be transferred to a female flower on that plant oranother plant in the field. This pollen transfer is accomplished byseveral naturally occurring insects, but most effectively by thehoneybee. Poor or ineffective pollination of watermelons results inbottle-neck fruits of long-fruited watermelon varieties. Inround-fruited varieties, poorly pollinated fruits can be flat-sided ormisshapen.

Watermelon has small flowers. Flowering begins about 8 weeks afterseeding. Flowers of watermelon are staminate (male), perfect(hermaphroditic), or pistillate (female), usually borne in that order onthe plant as it grows. Monecious types are most common, but there areandromonoecious (staminate and perfect) types, mainly the oldervarieties or accessions collected from the wild. In many varieties, thepistillate or perfect flowers are borne at every seventh node, withstaminate flowers at the intervening nodes. The flower ratio of typicalwatermelon varieties is 7 staminate to 1 pistillate, but the ratioranges from 4:1 to 15:1.

Watermelon is the only economically important cucurbit with pinnatifid(lobed) leaves; all of the other species have whole (nonlobed) leaves.The leaves are pinnately divided into three or four pairs of lobes,except for an entire-leaf (nonlobed) gene mutant controlled by the nl(nonlobed) gene. Watermelon growth habit is a trailing vine. The stemsare thin, hairy, angular, grooved, and have branched tendrils at eachnode. The stems are highly branched and up to 30 feet long, althoughthere are dwarf types (dw-1 and dw-2 genes) with shorter, less-branchedstems. Roots are extensive but shallow, with a taproot and many lateralroots.

Vine length of watermelon varies from dwarf to long. For example,‘Charleston Gray’ and ‘Jubilee’, large-fruited varieties, have vines upto 30 feet long. Short or medium length vines are well suited tovarieties with small or medium sized fruit. For example, ‘Sugar Baby’,‘New Hampshire Midget’, and ‘Petite Sweet’ are short vined, having vinelengths of between about six to about 12 feet and ‘Crimson Sweet’ hasintermediate vine length.

Dwarf mutants have been discovered in watermelon. Two genes causedwarfing when they are in homozygous recessive condition: dw-1 and dw-2.‘Kengarden’ has the genotype dw-1 dw-2. Another gene mutant (JapaneseDwarf, dw-2 dw-2) has increased branching from the crown.

Fruit size is an important consideration in a breeding program sincethere are different market requirements for particular groups ofshippers and consumers. The general categories are: icebox (<12 lb),small, sometimes called pee-wee (12-18 lb), medium (18-24 lb), large(24-32 lb), and giant (>32 lb). Fruit size is inherited in polygenicfashion, with an estimated 25 genes involved. Shippers in the UnitedStates work with particular weight categories, such as 18-24 lb forseeded and 14-18 lb for seedless. Researchers have developed threediploid seeded varieties with small fruit: New Hampshire Midget, Minileeand Mickylee. (Barnes, et al., Australian Journal of ExperimentalAgriculture. 1994. 34(5):673-679.)

The commercially available seedless watermelons have a round toround/oval to blocky shape with an average weight between 15-20 pounds.The length/width ratio (L/W ratio) for these commercial hybrids rangesfrom 1.2 (10×8.5 inches) to 1.7 (11.5×7 inches). There may beexceptional circumstances where the weight can go up to 32 pounds in thelarger extreme; and there may be also cases where fruits weigh as littleas 12-15 pounds in the smaller extreme. However the standard weight inthe seedless watermelon trade in the U.S. is that of 15-20 pounds. Theseranges of measurements and ratios apply for hybrid seedless watermelonsgrown in commercial fields and under conventional spacing between therows and within the rows.

Seedless triploid varieties are produced by crossing a tetraploid(2n=4x=44 chromosomes) inbred line as the female parent with a diploid(2n=2x=22) inbred line as the male parent of the hybrid. The reciprocalcross (diploid female parent) does not produce seeds. The resultinghybrid is a triploid (2n=3x=33). Triploid plants have three sets ofchromosomes, and three sets cannot be divided evenly during meiosis.This results in nonfunctional female and male gametes although theflowers appear normal. Since the triploid hybrid is female sterile, thefruit induced by pollination tend to be seedless. Unfortunately, thetriploid has no viable pollen, so it is necessary to plant a diploidvariety in the production field to provide the pollen that stimulatesfruit to form. Usually, one third of the plants in the field are diploidand two thirds are triploid, although production has been observed withas little as 20% diploids. Varieties should be chosen that could bedistinguished easily so the seeded diploid fruit can be separated fromthe seedless triploid fruit for harvesting and marketing.

Most of the tetraploid lines being used by the seed industry have grayrind so that, when crossed with a diploid line with striped rind, itwill be easy to separate self-pollinated progeny (which will be seededfruit from the female parent line) from cross-pollinated progeny (whichwill be seedless fruit from the triploid hybrid). The grower may discardthe gray fruit so they are not marketed as seedless watermelons bymistake. For example, if there is 4% of the fruit from the inbred parentthen 4% of total fruits will be unmarketable and reduces marketableyield.

A smaller fruited seedless watermelon, if available, would be desirablefor certain segments of the consumer market.

SUMMARY OF THE INVENTION

The present invention relates to a novel seedless watermelon having anaverage fruit weight of less than 12.0 pounds. The present inventionalso relates to a seedless watermelon seed, a seedless watermelon plant,seedless watermelon variety, and a seedless watermelon hybrid.

The present invention also relates to a novel method of producing smallfruited triploid watermelon seed by using small tetraploid and smalldiploid parental lines which are either transplanted or seeded into therow. The present invention also relates to a seedless watermelon plant,and a seedless watermelon hybrid which produces small seedless fruitshaving an average fruit weight of less than 12.0 pounds. Specifically,the claimed invention involves the following steps to produce seedlesswatermelon fruit:

1) planting triploid plants and diploid plants in one or more rows;

2) allowing said plants to mature and develop fruit; and

3) harvesting said fruit;

wherein said fruit has an average fruit weight of less than 12.0 pounds.

DEFINITIONS

In the description and tables which follow, a number of terms are used.In order to provide a clear and consistent understanding of thespecification and claims, including the scope to be given such terms,the following definitions are provided:

Average fruit weight. As used herein, “average fruit weight” means theaverage weight in pounds of all fruits harvested from one or morewatermelon plants of a specific genotype.

Average fruit length. As used herein, “average fruit length” means theaverage length of all fruits harvested from one or more plants of aspecific genotype.

Average fruit width. As used herein, “average fruit width” means theaverage width of all fruits harvested from one or more plants of aspecific genotype.

Average length to width ratio (L/W Ratio). As used herein, “length towidth ratio (L/W ratio) means the average length to width ratio from allfruits harvested from one or more plants of a specific genotype.

Average internode length. As used herein the term “average internodelength” means the average length of the internodes of a plant genotypemeasured in inches.

Lobed leaf. As used herein the term “lobed leaf” means a leaf having twoor more lobes.

Nonlobed leaf. As used herein the term “nonlobed leaf” means a leaf thatis not lobed.

Yield. As used herein, the term “yield” means the total weight in poundsof all watermelon fruit harvested per acre.

Plant. As used herein, the term “plant” includes plant cells, plantprotoplasts, plant cells of tissue culture from which watermelon plantscan be regenerated, plant calli, plant clumps and plant cells that areintact in plants or parts of plants such as pollen, flowers, seed,leaves, stems, rind, flesh and the like.

Quantitative Trait Loci (QTL). As used herein, the term “quantitativetrait loci (QTL)” refer to genetic loci that control to some degreenumerically representable traits that are usually continuouslydistributed.

Regeneration. Regeneration refers to the development of a plant fromtissue culture.

Seedless. As used herein, the term “seedless” means a watermelon fruitin which the embryo development is aborted and the seed developmentprocess has stopped before producing a mature viable seed. Seedlessfruit may contain traces of the developing seed and occasionally a seedcoat may form and become hard and have the appearance of a seed.

Plant diameter. As used herein, the term “plant diameter” means theaverage length of plant measurements in inches.

Single Gene Converted. Single gene converted or conversion plant refersto plants which are developed by a plant breeding technique calledbackcrossing wherein essentially all of the desired morphological andphysiological characteristics of an inbred are recovered in addition tothe single gene transferred into the inbred via the backcrossingtechnique or via genetic engineering.

Vine length. As used herein, the term “vine length” is the length of therunners (vines) and is measured in inches.

Average length of longest runner. As used herein, the term “averagelength of longest runner” means the average length of the longest runnerof the watermelon plant in inches.

Triploid plants. As used herein, “triploid plants” means plants ortransplants derived from planting triploid seeds or from micropropagation.

Diploid plants. As used herein, “diploid plants” means plants ortransplants derived from planting diploid seeds or from micropropagation.

Explosive rind. As used herein, “explosive rind” in watermelon is atrait where the rind is tender and can burst open when cut with a knife.The rind can also explode before the watermelon fruit reachesphysiological maturity and results in unmarketable fruit.

Thick rind. As used herein, “thick rind” is inherited in a polygenicfashion (controlled by more than one gene). Thick rind is proportionalwith the overall fruit diameter (fruit size). A rind thickness of ¾″ isacceptable for a 16 pound watermelon; but for a 10 pound watermelon therind should be of no more than ¼″ to be marketable.

Hollowheart: As used herein “hollowheart” is the characteristic ofseparation of tissue within the endocarp which can be caused by rapidfruit growth and weak tissue. The presence of Hollowheart (or onevariant which is placental detachment) is affected by environment, butcan also be selected against in the development of inbred lines. Thegenetic control of this undesirable trait is not understood.

Rind pattern: As used herein, the “rind pattern” is the coloration ofthe rind in watermelons which can vary from light green, often termedgray, to medium green to very dark green which appears to be almostblack. In addition, the rind may have stripes of various designs whichare typical of a variety or type. Therefore the terms ‘tiger stripe’,‘mottle stripe’, ‘dark mottle stripe’, etc. are used to identify variouspatterns.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a novel method of producing smalltriploid watermelon fruit which involves the use of both small fruitedtetraploid and small fruited diploid parental lines. The presentinvention also relates to a watermelon plant, a watermelon inbred and awatermelon hybrid which can be used to produce fruits having an averagefruit weight of less than 12.0 pounds.

In the present invention, small seedless triploid seeds and plants areproduced by crossing a small tetraploid (2n=4x=44 chromosomes) inbredline as the female parent with a small diploid (2n=2x=22) inbred line asthe male parent of the hybrid. The reciprocal cross (diploid femaleparent) does not produce seeds. The resulting hybrid is a triploid(2n=3x=33). Triploid plants have three sets of chromosomes, and threesets cannot be divided evenly during meiosis. This results innonfunctional female and male gametes although the flowers appearnormal. Since the triploid hybrid is female sterile, the fruit inducedby pollination tend to be seedless. Unfortunately, the triploid has noviable pollen, so it is necessary to plant a diploid variety in theproduction field to provide the pollen that stimulates fruit to form.Usually, one third of the plants in the field are diploid and two thirdsare triploid, although production has been observed with as little as20% diploids. Varieties should be chosen that could be distinguishedeasily so the seeded diploid fruit can be separated from the seedlesstriploid fruit for harvesting and marketing.

The present invention is a novel method which crosses a small-fruitedtetraploid as the seed parent and a small-fruited diploid as the maleparent to produce triploid seed and plants of a small fruited seedlesswatermelon having an average fruit weight of less than 12.0 pounds. Inthe present invention, the tetraploid and diploid parental lines used tocreate small fruited triploids have been selected and bred to have smallfruit and small seeds which produce small seed traces or pips in thetriploid hybrid. The fruits produced by growing the triploid hybrid thatresults from this pollination and method are genetically small and areseedless. This novel method allows the triploid hybrid to producesmaller than conventional fruit sizes that can be grown using standardcultural practices and have the advantage to the consumer of being a“one-serving” product. The use of this novel small fruited seedlesswatermelon also allows easier harvesting of the triploid fruitsproduced, since the weight is less than the fruits of currently usedseedless hybrids.

In another embodiment of the present invention, the small seedlesswatermelon fruits have a length of between about 6 to about 11 inches.

In another embodiment of the present invention the small seedlesswatermelon fruits have a width of between about 5 inches to about 9inches.

In another embodiment of the present invention, the small seedlesswatermelon fruits have a length to width ratio (L/W ratio) of betweenabout 1. to about 1.9.

The established plants in a field of the present invention can bedeveloped from the following methods: 1) planting seeds or any portionsof seed; 2) primed or coated seed, or any portions of the seed; 3)plants, or portions thereof, derived from tissue culture or cellculture; 4) cuttings; and 5) planting transplants into the field.

The triploid and diploid seeds of the present invention can be mixedprior to planting and then sowed or the triploid seed can first beplanted, followed by planting the diploid seed or vice versa, dependingon expected pollination dates.

Previously, researchers have developed and released three diploidvarieties with small fruit: “New Hampshire Midget” (NUM), “Minilee”(MN), and “Mickylee” (MK). The varieties New Hampshire Midget, Minileeand Mickylee all are diploid watermelons with seeds and have a diploidchromosome number (2n=2x=22). To make a triploid (seedless) watermelonhybrid one of the lines' (that will become the seed parent or femaleparent) will need to have the chromosome number doubled (2n=4x=44chromosomes) to produce tetraploids.

When these three diploid lines (NHM, MN, MK) are doubled this results ina number of problems which prevent the production of triploid seedlesswatermelon. One problem is the presence of hard seed coats in thetriploid hybrids resulting from these tetraploids. The lines MN and MKwhen doubled to become tetraploid are highly sterile (particularlyfemale sterile) and produce from zero to only a few seeds per fruit.This results in a problem for seed increase of the line and also is abig problem at the time of making the triploid hybrid since often noseeds are produced in the tetraploid. Besides the problem of highsterility when in the tetraploid phase and the problems with hard seedcoat in the triploids, additional problems include: hollow heart,placental detachment from the rest of the flesh, thick rind, and in thecase of NHM the problem of explosive rind. Explosive rind is a traitthat causes the fruit to split open before (or at the time) the fruitreaches maturity. This ruins the production of the commercial watermelonfruit. Another disadvantage with the MN, MK and NHM diploid lines isthat they have a light green color rind pattern (so called “gray rind”).People prefer to consume watermelons with different rind patterns thangray rind (i.e., dark green, mottle striped, etc.).

Hard seed coats, thick rind, explosive rind and hollow heartcharacteristics in the fruit make the product unsatisfactory forcommercial marketing purposes. The diploid versions of MN, MK and NHMare also unattractive to the consumer because they are full of seeds.

The present invention resulted in seedless watermelon hybrids, andeliminated the negative traits associated with these previous lines.Unexpectedly the lines of the present invention listed in Tables 1-3 donot have the problems of: 1) being highly female sterile; 2) producinghard seed coats in the triploid (seedless) fruit; 3) hollow heart, 4)thick rind, and 5) explosive rind.

Also, unexpectedly small seedless watermelon fruit of less than 12pounds were produced where the seed parents (tetraploid) do not havehigh sterility. It was also unexpected that a seedless watermelon fruitof less than 12 pounds can be produced without the negative traits of 1)explosive rind, 2) hollow heart, and 3) a gray rind pattern.

EXAMPLES

The present invention is further detailed in the following Examples,which are offered by way of illustration and are not intended to limitthe invention in any manner. Standard techniques well known in the artor the techniques specifically described are utilized.

Example 1 Tetraploid and Diploid Parental Lines

Numerous tetraploid parental lines of the present invention have beendeveloped and are listed in Table 1. Also listed in Table 1 are numerousdiploid parental lines of the present invention with small fruits andsmall seed size which can be used in the method of the presentinvention. There are approximately 31-35 diploid lines that have beencrossed with other small tetraploid plants of the present invention toproduce triploid hybrids which then can be grown to produce smallseedless fruit.

TABLE 1 Diploid and Tetraploid Parental Lines Number/ID Rind PatternFlesh Color Fruit Shape Ploidy 1671 Gray Red Round/Oval Tetraploid 1674Gray Red Round Tetraploid 1696 Gray Red Oval Tetraploid 1670 Gray RedRound Tetraploid 1675 Gray Red Round Tetraploid 1672 Gray Red RoundTetraploid 1885 Dark green Red Round Tetraploid 2526 Gray RedOval/Blocky Diploid 2321 Mottle stripe Red Blocky Diploid 2201 TigerStripe Red Round Diploid 2142-1 Dark Green Red Round/Oval Diploid 2552-1Mottle stripe Red Oval Diploid 2841 Tiger stripe Red Round/Oval Diploid3128 Dark green Red Round Diploid 02-6003 Dark Mottle Stripe Red/orangeBlocky Tetraploid 02-6107 Dark Mottle Stripe Red Blocky Tetraploid02-6154 Mottle Stripe Red Round Tetraploid 02-6210 Mottle Stripe RedRound Tetraploid 02-6278 Dark Mottle Stripe Red Round Tetraploid 02-6279Dark Mottle Stripe Red Round Tetraploid 02-6339 Mottle Stripe Red RoundTetraploid 02-6495 Dark Green/Black Red/orange Round Tetraploid 02-6605Gray Red Oval/Blocky Tetraploid 02-6614 Gray Red Blocky Tetraploid02-6696 Gray Red Round Tetraploid 02-6711 Gray Red Round Tetraploid02-6712 Gray Red Round Tetraploid 02-6713 Gray Red Round Tetraploid02-6716 Gray Red Round Tetraploid 02-6757 Gray Red Round Tetraploid110-4700 Gray Red Round/oval Tetraploid 02F1862-1 Tiger Stripe YellowRound Tetraploid 02F1862-2 Tiger Stripe Yellow Round Tetraploid02F1862-3 Gray Yellow Round Tetraploid 02F1811-1 Dark Green Red RoundTetraploid 02F2427-1 Dark Mottle Stripe Red Round Tetraploid 02F2434-1Dark Green Red Round Tetraploid 02F1616-1 Tiger Stripe Yellow RoundDiploid 02F1632-1 Gray Yellow Round Diploid 02F1633-1 Gray Yellow RoundDiploid 02-5607 Gray Red Blocky Diploid 02-5612 Gray Red Round/ovalDiploid 02-5618 Dark Green Red Round/oval Diploid 02-5624 Dark Green RedRound/oval Diploid 02-5625 Tiger Stripe Red Round/oval Diploid 02-5626Tiger Stripe Red Round Diploid 02-5628 Dark Green Red Round Diploid02-5629 Dark Green Red Round/oval Diploid 02-5631 Mottle Stripe RedRound/oval Diploid 02-5632 Mottle Stripe Red Round/oval Diploid 02-5640Mottle Stripe Red Round Diploid 02-5661 Mottle Stripe Red ElongatedDiploid 02-5668 Mottle Stripe Red Elongated Diploid 02-5693 Gray RedElongated Diploid 02-5695 Gray Red Blocky Diploid 02-5758 Dark Green RedBlocky Diploid 02-5813 Mottle Stripe Red Round Diploid 02-5827 MottleStripe Red Round Diploid 02-5853 Mottle Stripe Red Round/oval Diploid02-5861 Mottle Stripe Red Round/oval Diploid 110-3128 Dark Green RedRound/oval Diploid

Example 2 Seedless Watermelon with Small Fruit ‘01-1703’

The triploid hybrid plant ‘01-1703’ produces a small fruited seedlesswatermelon with an average fruit weight of between 8.0 and 9.0 pounds.This triploid of the present invention results from crossing the smalltetraploid line ‘1671’ with the small diploid line ‘2201.’ This smallersize of seedless watermelon fruit has not been commercially availablefrom current commercial seedless production. The small fruitedwatermelons currently commercially available to the grower all have adiploid genetic background and therefore produce only seeded fruit.Another unique characteristic of hybrid ‘01-1703’ is the firmer thannormal flesh and a very reduced size of seed traces or pips.

Vine type: VineTotal vine length: 400 cmInternode length: 11 cmMaturity: Mid-season −˜85 days

Similar to: Petite Sweet

Leaf type: LobedDistance crown to fruit: 216 cmFruit weight: 8-9 lbsFruit shape: RoundFruit size (cm): 18×18Rind thickness (cm): 2.5 at stem end; 2.0 mid fruit; 1.0 at blossom endFlesh color: RedTexture: Firm and crispSeed traces size: 6 mm×4 mmBlossom scar diameter (cm): 1.2

Brix: 11.20% Stripe: Like Crimson Sweet

Number of main runners: 4

Example 3 Seedless Watermelon with Small Fruit ‘01-1714’

The triploid hybrid ‘01-1714’ of the present invention produces smallfruited seedless watermelon having an average fruit weight of less than10 pounds. Seed of this hybrid is produced by crossing the tetraploidline ‘1671’ with the diploid line ‘2142.’ This hybrid possesses a mediumto medium-dark green rind which is the result of crossing a graytetraploid to a dark green diploid. Currently, there are no commerciallysold seedless hybrids which have smaller fruit size, with small seedtraces, and a very firm flesh.

Vine type: VineTotal vine length: 490 cmInternode length: 11 cmMaturity: Mid-season −˜85 daysSimilar to: Minilee with shadow rind patternLeaf type: LobedDistance crown to fruit: 190 cmFruit weight: 8-9 lbsFruit shape: Round/OvalFruit size (cm): 21×17.5Rind thickness (cm): 2.0 at stem end; 1.7 mid fruit; 1.0 at blossom endFlesh color: Red to red/orangeTexture: Firm and crispSeed traces size: 5 mm×3 mmBlossom scar diameter (cm): 1.1

Brix: 12.80%

Stripe: Shadow type (DMS on DG background)Number of main runners: 3

Example 4 Seedless Watermelon with Small Fruit ‘02-8518’

This hybrid of the present invention produces a small seedless fruitsize with an average fruit weight of about 9.0 pounds. Hybrid ‘02-8518’seed is produced by crossing the small tetraploid line ‘1885’ with thesmall diploid line ‘3128.’ The seeded hybrids of the Sugar Baby type areknown for their softer than desired flesh. The fruit produced fromseedless hybrid ‘02-8518’ of the present invention have a very firmflesh in addition to very small seed traces and a higher fruit count.The small fruited diploid parental line used in this cross is veryproductive and contributes to the higher fruit count per plant.

Vine type: VineTotal vine length: 320 cmInternode length: 8 cmMaturity: Early mid-season −˜80 days

Similar to: Sugar Baby

Leaf type: LobedDistance crown to fruit: 162 cmFruit weight: 9 lbsFruit shape: RoundFruit size (cm): 20×18.5Rind thickness (cm): 2.0 at stem end; 1.2 mid fruit; 1.3 at blossom endFlesh color: Red to red/orangeTexture: Medium firmSeed traces size: 7 mm×3 mmBlossom scar diameter (cm): 1

Brix: 13.40%

Stripe: Black/dark green, no stripeNumber of main runners: 4

Example 5 PS1100-1714, Harvested Boxes of Watermelon Fruits

The data in Table 2 shows the number of packed fruits. Fruits that wereconsidered of good marketable quality and of the targeted size. Plantingdate of the data is June 3 to Jun. 9, 2002. Total number of plants isapproximately 1,800. Row distance is 60 inches and plant distance inrows is 24 inches.

TABLE 2 Seedless Small Miniwatermelon PS1100-1714 Harvested Boxes perPeriod Fruit Size Category # Pick 5″ 6″ 8″ Boxes Date 1^(st) 36 31 1 68Aug. 1, 2002  2^(nd) 41 49 6 96 Aug. 5, 2002  3^(rd) 4 4 4 12 Aug. 7,2002  4^(th) 27 29 7 63 Aug. 9, 2002  5^(th) 27 71 9 107 Aug. 13, 20026^(th) 1 4 4 9 Aug. 16, 2002 7^(th) 24 43 3 70 Aug. 19, 2002 8^(th) 4 149 27 Aug. 21, 2002 Total # Boxes 164 245 43 452 Total # Fruits 820 1470344 2634

Example 6 Small Seedless Triploid Hybrids Produced

Table 3 shows additional small seedless triploid hybrids that wereproduced in Summer 2002 in Gilroy, Calif. and were grown in Colina,Mexico in Fall 2002.

TABLE 3 Additional Examples of Seedless (triploid) Hybrids with smallfruit Number/ID Female Parent Male Parent Ploidy 5331 110-1005  02-5612Triploid 5332 CB662-1 02-5618 Triploid 5333 CB663-1 110-3128  Triploid5334 CB663-1 02-5695 Triploid 5335 110-1005  01-3683 Triploid 5336110-1005  02-5640 Triploid 5337 110-1005  02-5853 Triploid 5338110-4700  02-5625 Triploid 5339 110-4700  02-5626 Triploid 5340110-4700  02-5631 Triploid 5341 110-4700  02-5632 Triploid 5342110-4700  02-5668 Triploid 5343 110-4700  02-5827 Triploid 5344110-4700  02-5861 Triploid 5345 02-6003 02-5607 Triploid 5346 02-600302-5861 Triploid 5347 02-6107 02-5640 Triploid 5348 02-6154 02-5640Triploid 5349 02-6210 02-5640 Triploid 5350 02-6278 02-5625 Triploid5351 02-6278 02-5668 Triploid 5352 02-6278 02-5758 Triploid 5353 02-627802-5827 Triploid 5354 02-6279 02-5626 Triploid 5355 02-6279 02-5640Triploid 5356 02-6279 02-5861 Triploid 5357 02-6339 02-5640 Triploid5358 02-6495 110-3128  Triploid 5359 02-6495 01-3689 Triploid 536002-6495 02-5607 Triploid 5361 02-6495 02-5618 Triploid 5362 02-649502-5626 Triploid 5363 02-6495 02-5629 Triploid 5364 02-6495 02-5668Triploid 5365 02-6495 02-5693 Triploid 5366 02-6495 02-5758 Triploid5367 02-6495 02-5861 Triploid 5368 02-6605 110-3128  Triploid 536902-6614 110-3128  Triploid 5370 02-6696 110-3128  Triploid 5371 02-671102-5624 Triploid 5372 02-6711 02-5661 Triploid 5373 02-6711 02-5668Triploid 5374 02-6711 02-5813 Triploid 5375 02-6712 02-5628 Triploid5376 02-6713 02-5607 Triploid 5377 02-6713 02-5612 Triploid 5378 02-671302-5632 Triploid 5379 02-6716 02-5632 Triploid 5380 02-6716 02-5853Triploid 5381 02-6757 110-3128  Triploid 5382 02-6711 02-5625 Triploid

When the term inbred watermelon plant is used in the context of thepresent invention, this also includes any transgenes and single geneconversions of that inbred. The term single gene converted plant as usedherein refers to those watermelon plants which are developed by a plantbreeding technique called backcrossing wherein essentially all of thedesired morphological and physiological characteristics of an inbred arerecovered in addition to the single gene transferred into the inbred viathe backcrossing technique. Backcrossing methods can be used with thepresent invention to improve or introduce a characteristic into theinbred. The term backcrossing as used herein refers to the repeatedcrossing of a hybrid progeny back to one of the parental watermelonplants for that inbred. The parental watermelon plant which contributesthe gene for the desired characteristic is termed the nonrecurrent ordonor parent. This terminology refers to the fact that the nonrecurrentparent is used one time in the backcross protocol and therefore does notrecur. In a typical backcross protocol, the original inbred of interest(recurrent parent) is crossed to a second inbred (nonrecurrent parent)that carries the single gene of interest to be transferred. Theresulting progeny from this cross are then crossed again to therecurrent parent and the process is repeated until a watermelon plant isobtained wherein essentially all of the desired morphological andphysiological characteristics of the recurrent parent are recovered inthe converted plant, in addition to the single transferred gene from thenonrecurrent parent.

The selection of a suitable recurrent parent is an important step for asuccessful backcrossing procedure. The goal of a backcross protocol isto alter or substitute a single trait or characteristic in the originalinbred. To accomplish this, a single gene of the recurrent inbred ismodified or substituted with the desired gene from the nonrecurrentparent, while retaining essentially all of the rest of the desiredgenetic, and therefore the desired physiological and morphological,constitution of the original inbred. The choice of the particularnonrecurrent parent will depend on the purpose of the backcross, one ofthe major purposes is to add some commercially desirable, agronomicallyimportant trait to the plant. The exact backcrossing protocol willdepend on the characteristic or trait being altered to determine anappropriate testing protocol. Although backcrossing methods aresimplified when the characteristic being transferred is a dominantallele, a recessive allele may also be transferred. In this instance itmay be necessary to introduce a test of the progeny to determine if thedesired characteristic has been successfully transferred.

Many single gene traits have been identified that are not regularlyselected for in the development of a new inbred but that can be improvedby backcrossing techniques. Single gene traits may or may not betransgenic, examples of these traits include but are not limited to,male sterility, herbicide resistance, resistance for bacterial, fungal,or viral disease, insect resistance, male fertility, enhancednutritional quality, industrial usage, yield stability and yieldenhancement. These genes are generally inherited through the nucleus.Some known exceptions to this are the genes for male sterility, some ofwhich are inherited cytoplasmically, but still act as single genetraits. Several of these single gene traits are described in U.S. Pat.Nos. 5,777,196; 5,948,957 and 5,969,212, the disclosures of which arespecifically hereby incorporated by reference.

A further aspect of the invention relates to tissue culture ofwatermelon plants designated ‘1671’. As used herein, the term “tissueculture” indicates a composition comprising isolated cells of the sameor a different type or a collection of such cells organized into partsof a plant. Exemplary types of tissue cultures are protoplasts, calli,plant clumps, and plant cells that can generate tissue culture that areintact in plants or parts of plants, such as embryos, pollen, flowers,leaves, roots, root tips, anthers, and the like. In a preferredembodiment, tissue culture is embryos, protoplast, meristematic cells,pollen, leaves or anthers. Means for preparing and maintaining planttissue culture are well known in the art. By way of example, a tissueculture comprising organs such as tassels or anthers, has been used toproduce regenerated plants. (See U.S. Pat. Nos. 5,445,961; 5,322,789;5,948,957 and 5,969,212, the disclosures of which are incorporatedherein by reference).

DEPOSIT INFORMATION

Watermelon seeds of ‘1671’ have been placed on deposit with the AmericanType Culture Collection (ATCC), 10801 University Blvd., Manassas, Va.20110, under Deposit Accession Number PTA-4858 on Dec. 13, 2002.

Although the foregoing invention has been described in some detail byway of illustration and example for purposes of clarity andunderstanding, it will be obvious that certain changes and modificationsmay be practiced within the scope of the invention, as limited only bythe scope of the appended claims.

1-24. (canceled)
 25. A fertile tetraploid watermelon plant, or a partthereof, wherein said tetraploid watermelon plant is capable ofproducing a watermelon fruit when grown under standard culturalpractices with a weight of less than 12.0 pounds, and does not have oneor more negative traits selected from the group consisting of explosiverind, hollow heart, gray rind, and producing a triploid hybrid seed witha hard seed coat, and wherein the rind color of said watermelon fruit islight green or medium green.
 26. The fertile tetraploid watermelonplant, or the part thereof, of claim 25, wherein said watermelon fruithas a length of between 6 to 11 inches.
 27. The fertile tetraploidwatermelon plant, or the part thereof, of claim 25, wherein saidwatermelon fruit has a width of between 5 to 9 inches.
 28. The fertiletetraploid watermelon plant, or the part thereof, of claim 25, whereinsaid watermelon fruit has a length to width ratio (L/W ratio) of between1.0 to 2.0.
 29. The fertile tetraploid watermelon plant, or the partthereof, of claim 25, wherein said tetraploid watermelon plant includesa single gene conversion selected from the group consisting of malesterility, herbicide resistance, bacterial resistance, fungalresistance, viral resistance, insect resistance, male fertility,enhanced nutritional quality, industrial usage, yield stability andyield enhancement.
 30. The fertile tetraploid watermelon plant, or thepart thereof, of claim 25, wherein said part is selected from the groupconsisting of a cell, a plant protoplast, a tissue culture of cells,plant calli, a pollen, a flower, a seed, a leaf, a stem, a rind, andwatermelon flesh.
 31. The fertile tetraploid watermelon plant, or thepart thereof, of claim 25, wherein said tetraploid watermelon plant is aprogeny of tetraploid watermelon plant line 1671, wherein arepresentative sample of seed of said line 1671 has been deposited withthe American Type Culture Collection (ATCC) under ATCC Accession No.PTA-4858.
 32. A progeny watermelon plant, or a part thereof, oftetraploid watermelon plant line 1671, wherein a representative sampleof seed of said line 1671 has been deposited with the ATCC under ATCCAccession No. PTA-4858, and said progeny watermelon plant is capable ofproducing a watermelon fruit with a weight of less than 12.0 pounds, anddoes not have one or more negative traits selected from the groupconsisting of explosive rind, hollow heart, gray rind, and producing atriploid hybrid seed with a hard seed coat, and wherein the rind colorof said watermelon fruit is selected from the group consisting ofstriped, mottle stripe, dark mottle stripe, tiger stripe, gray, lightgreen, and medium green.
 33. The progeny watermelon plant, or the partthereof, of claim 32, wherein said progeny watermelon plant istetraploid.
 34. The progeny watermelon plant, or the part thereof, ofclaim 32, wherein said progeny watermelon plant is triploid.
 35. Theprogeny watermelon plant, or the part thereof, of claim 32, wherein saidprogeny watermelon plant is a hybrid.
 36. The progeny watermelon plant,or the part thereof, of claim 32, wherein said progeny tetraploidwatermelon plant includes a single gene conversion selected from thegroup consisting of male sterility, herbicide resistance, bacterialresistance, fungal resistance, viral resistance, insect resistance, malefertility, enhanced nutritional quality, industrial usage, yieldstability and yield enhancement and said line 1671 is a recurrentparent.
 37. The progeny watermelon plant, or the part thereof, of claim32, wherein said part is selected from the group consisting of a cell, aplant protoplast, a tissue culture of cells, plant calli, a pollen, aflower, a seed, a leaf, a stem, a rind, and watermelon flesh.
 38. Afertile progeny tetraploid watermelon plant, or a part thereof,obtainable by crossing a first tetraploid watermelon plant of line 1671with a second tetraploid watermelon plant, wherein a representativesample of seed of said line 1671 has been deposited with the ATCC underATCC Accession No. PTA-4858, and said fertile progeny tetraploidwatermelon plant is capable of producing a watermelon fruit with aweight of less than 12.0 pounds, and does not have one or more negativetraits selected from the group consisting of explosive rind, hollowheart, gray rind, and producing a triploid hybrid seed with a hard seedcoat, and wherein the rind color of said watermelon fruit is selectedfrom the group consisting of striped, mottle stripe, dark mottle stripe,tiger stripe, gray, light green, and medium green.
 39. The fertileprogeny tetraploid watermelon plant, or the part thereof, of claim 38,wherein said tetraploid watermelon plant is an F₁ progeny of said line1671.
 40. The fertile progeny tetraploid watermelon plant, or the partthereof, of claim 38, wherein said second tetraploid watermelon plantcomprises a single gene trait.
 41. The fertile progeny tetraploidwatermelon plant, or the part thereof, of claim 38, wherein said progenytetraploid watermelon plant includes a single gene conversion selectedfrom the group consisting of male sterility, herbicide resistance,bacterial resistance, fungal resistance, viral resistance, insectresistance, male fertility, enhanced nutritional quality, industrialusage, yield stability and yield enhancement and said first tetraploidwatermelon plant is a recurrent parent.
 42. The fertile progenytetraploid watermelon plant, or the part thereof, of claim 41, whereinsaid single gene conversion is male sterility and said male sterility iscytoplasmic male sterility.
 43. The fertile progeny tetraploidwatermelon plant, or the part thereof, of claim 38, wherein said part isselected from the group consisting of a cell, a plant protoplast, atissue culture of cells, plant calli, a pollen, a flower, a seed, aleaf, a stem, a rind, and watermelon flesh.
 44. The fertile progenytetraploid watermelon plant, or the part thereof, of claim 38, whereinsaid watermelon fruit has a length of between 6 to 11 inches.
 45. Thefertile progeny tetraploid watermelon plant, or the part thereof, ofclaim 38, wherein said watermelon fruit has a width of between 5 to 9inches.
 46. The fertile progeny tetraploid watermelon plant, or the partthereof, of claim 38, wherein said watermelon fruit has a length towidth ratio (L/W ratio) of between 1.0 to 2.0.
 47. A method of producinga triploid watermelon seed comprising: a) crossing a fertile tetraploidwatermelon plant that produces watermelon fruit with an average fruitweight of less than 12.0 pounds, with a small fruited diploid watermelonplant, wherein said tetraploid watermelon plant does not have one ormore negative traits selected from the group consisting of explosiverind, hollow heart, gray rind, and producing a triploid hybrid seed witha hard seed coat, and wherein the rind color of said watermelon fruit isselected from the group consisting of gray, light green, and mediumgreen; and b) harvesting the resultant triploid watermelon seed that,when grown into a plant, produces a seedless watermelon fruit.
 48. Themethod of claim 47, wherein said triploid watermelon seed does not havea hard seed coat.
 49. The method of claim 47, wherein a plant grown fromsaid triploid watermelon seed is capable of producing a seedlesswatermelon fruit with a weight of less than 12.0 pounds.
 50. The methodof claim 47, wherein a plant grown from said triploid watermelon seeddoes not have one or more negative traits selected from the groupconsisting of being highly female sterile, hollow heart, thick rind andexplosive rind.
 51. A fertile tetraploid watermelon plant, or a partthereof, wherein said tetraploid watermelon plant is capable ofproducing a watermelon fruit with a weight of less than 12.0 pounds, anddoes not have one or more negative traits selected from the groupconsisting of explosive rind, hollow heart, gray rind, and producing atriploid hybrid seed with a hard seed coat, the rind color of saidwatermelon fruit is selected from the group consisting of gray, lightgreen, and medium green, said tetraploid watermelon plant shares agenetic constitution with watermelon plant line 1671, said line 1671having a representative sample of seed deposited with the American TypeCulture Collection (ATCC) under ATCC Accession No. PTA-4858, saidgenetic constitution provides for the production of a watermelon fruitwith a weight of less than 12.0 pounds, and lack of one or more negativetraits selected from the group consisting of explosive rind, hollowheart, gray rind, and producing a triploid hybrid seed with a hard seedcoat.
 52. The fertile tetraploid watermelon plant, or the part thereof,of claim 51, wherein said watermelon fruit has a length to width ratio(L/W ratio) of between 1.0 to 2.0.
 53. The fertile tetraploid watermelonplant, or the part thereof, of claim 51, wherein said tetraploidwatermelon plant includes a single gene conversion selected from thegroup consisting of male sterility, herbicide resistance, bacterialresistance, fungal resistance, viral resistance, insect resistance, malefertility, enhanced nutritional quality, industrial usage, yieldstability and yield enhancement.
 54. The fertile tetraploid watermelonplant, or the part thereof, of claim 51, wherein said part is selectedfrom the group consisting of a cell, a plant protoplast, a tissueculture of cells, plant calli, a pollen, a flower, a seed, a leaf, astem, a rind, and watermelon flesh.
 55. The fertile tetraploidwatermelon plant, or the part thereof, of claim 25, wherein said rind isstriped, mottle striped, dark mottle striped, or tiger striped.
 56. Thefertile progeny tetraploid watermelon plant, or a part thereof, of claim38, wherein said rind is striped, mottle striped, dark mottle striped,or tiger striped.
 57. The fertile progeny tetraploid watermelon plant,or a part thereof, of claim 51, wherein said rind is striped, mottlestriped, dark mottle striped, or tiger striped.